There has been known a monitoring system making use of a picture telephone or the like. For instance, Japanese Patent Laid-Open Publication No. 2002-84531 discloses a remote-controlled mobile monitoring robot system as a system for remotely monitoring situations inside an empty office or an empty home without requiring installation of a number of monitoring cameras and with only one unit of mobile robot camera from a center, and in this system, a communication terminal unit for a picture telephone or the like and a remote control unit are provided at the center; a communication terminal unit for a picture telephone or the like connected to the communication terminal unit at the center via a public communication network, an AV tuner, a transmitter, and a mobile robot camera are provided at a user's home; and AV information with the mobile robot camera is monitored with the communication terminal unit at the center via the AV tuner, communication terminal, and public communication network by remotely controlling the mobile robot camera at the user's home with the remote control unit at the center via the communication terminal unit, public communication network, communication terminal unit, and transmitter.
In this system, in addition to many facilities for controlling a camera/microphone section (mobile robot camera), many other facilities are required for both the controlling side and controlled side, and a vast amount of capital investment is required.
Further in association with the progress in the field of a mobile telephone, for instance, Japanese Patent Laid-Open Publication No. 2002-57808 discloses a mobile telephone having the function of a picture telephone capable of real time image transfer based on the communication system of the next generation with the high transfer capability such as W-CDMA, which can also be used as a remote monitor or a simple monitor for remote medical services. With the mobile telephone, the side sending a request for controlling a camera to a connected site transfers a control command generated in the control section by performing various key operations to a radio transmitting/receiving section and transmits the control command as a radio signal from an antenna. The side with the camera remotely controlled analyzes the control command received via the antenna and the radio transmitting/receiving section with the control section, and carries out an operation corresponding to the received control command. Japanese Patent Laid-Open Publication No. 2002-57808 also describes that an external I/O section controls over operations of a camera according to control data transmitted from the control section.
In the invention described in Japanese Patent Laid-Open Publication No. 2002-57808, specific control signals are transmitted to a receiving side for controlling various types of functions in the controlled side, so that products in both the controlling side and controlled side are required to have the communicating function for remote monitoring, and therefore there is the disadvantage that the versatility is not ensured. Further in the invention described in the Publication, the controlled side demands authentication with a password or the like to allow or inhibit control, but in the case of authentication with a password or the like, hacking is possible, which disadvantageously lowers the reliability of the system.